Almost all onboard video connections disable when you plug in a graphics card. I didn't read your motherboard manual but you can check that.
So the 730 may be OK but if your VGA is plugged in I find many struggle to extend the desktop.
No Windows version noted so here's a video on this for Windows 10.
https://www.youtube.com/watch?v=Yl7U4uGZE5M
Hello there!
I have an Nvidia GT 730 graphics card, Asrock H61M-HVS motherboard, Sandy Bridge Intel i3 and 8GB Rams. I also have an HD ready Samsung tv. My graphics card, motherboard and TV have HDMI ports but none of them are interacting with each other.
I have bought a new monitor, Full HD, 1920*1080, HDMI signal undetected.
I tried downloading and installing a new graphics driver, not working.
Tried differenct HDMI cables, not working.
Tried turning everything off, plugging in the HDMI cable, then turning everything back on. None of this works
My monitor works fine with VGA.
I have looked in my BIOS if there is a possibility to turn on HDMI, but there isn't.
Why I don't understand is because my PC detects both the monitor and TV, but it's not sending the signal, nothing is showing on any of the screens.
Do you guys have any ideas about what to do?
The graphics card still has warranty.
Thanks in advance!

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic